For the production of steel billets in the form of slabs, it is conventional to employ ingot molds whose free cross-sectional surface at the mold outlet corresponds to the desired billet format.
A corresponding ingot mold for a billet with oval cross section is known from U.S. Pat. No. 2,767,448. This mold is a corresponding ingot mold for a billet with oval cross so-called block ingot mold, i.e. the cross section of the ingot mold cannot be changed and it is not suitable for adjusting different billet formats. Further, an ingot mold is known from the prior art through DE 35 01 422 C2, whose narrow side walls can be adjusted to different billet dimensions and whose pour-in opening has an oval crosssectional surface. The ingot mold tapers toward the outlet end in such a way that the broad sides of the slab form parallel walls, while the narrow side walls diverge from the pour-in side to the pouring side, but retain their concave shape. Such an ingot mold is likewise known from EP 0 249 146 and U.S. Pat. No. 4,716,955.
Ingot molds are known from DE-A1 36 27 991 and WO 87/00099 which have plane surfaces on the narrow sides and convex broad sides along the entire height of the mold.
It must be noted that when using any of these ingot molds deformations occur in the billet shell when the billet passes through the mold, obviously because the billet shells contact the mold wall in different ways, and these deformations can result in cracks in the billet shell.
The object of the present invention is to improve the cooling conditions inside the continuous casting ingot mold and to prevent a blocking of the movement of the billet also in the width direction when the billet passes through the ingot mold so as to eliminate the risk of longitudinal cracks and fissures as far as possible.